getblockhash: throw JSONRPCError (not runtime_error)

src/rpcblockchain.cpp

@@ -225,7 +225,7 @@ Value getblockhash(const Array& params, bool fHelp)
 
     int nHeight = params[0].get_int();
     if (nHeight < 0 || nHeight > chainActive.Height())
-        throw runtime_error("Block number out of range.");
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Block height out of range");
 
     CBlockIndex* pblockindex = chainActive[nHeight];
     return pblockindex->GetBlockHash().GetHex();